Ah, warm weather! Have dinner on the patio or sit on the porch. But warmth brings mosquitoes to ruin your outdoor fun. Spraying can be messy, but here is one option to avoid mosquito bites without the mess: mosquito coils. Our guide will tell you everything you need to know about safely using this method of mosquito control.
What is a Mosquito Coil?
A mosquito coil is a spiral that is composed of a binding agent mixed with either insecticide or a repellent. As it burns, it releases the insecticide or repellent to keep mosquitoes at bay. They can be hung, mounted on a stand, or burned in a ceramic, metal, or terra-cotta holder.
How Long Have Mosquito Coils Been Used?
In the late 19th century, the insecticide pyrethrum was mixed with sawdust and burned to repel mosquitoes in Japan. Japanese entrepreneur Eiichiro Ueyama tried to create a longer-lasting product using starches. However, the incense sticks he made didn’t have a long burn time.
His wife, Yuki, suggested making the sticks longer and curling them into a spiral.
Her suggestion worked, and the first coils were marketed in 1902. Coils were hand-rolled until the late 1950s when mass production methods arrived. At that point, they began to catch on in the U.S. and other countries.
What Ingredients Are in a Mosquito Coil?
A mosquito coil is an insecticide or a repellent mixed with a binding agent that also acts as fuel. Some insecticides are:
Pyrethrum powder: This comes from the crushed whole flowers of chrysanthemum cinerariifolium, a type of chrysanthemum plant also known as pyrethrum. It has a toxic effect on insects’ nervous systems.
Pyrethrins: This is the more refined extract of pyrethrum powder. Pyrethrins have been used since the 1950s.
Pyrethroids: This is a group of synthetic pesticides similar to pyrethrum. The first synthetic pyrethrin, d-trans-allethrin, was formulated in the late 1940s. Another synthetic pyrethrin, metofluthrin, is considered to be very effective against mosquitoes.
Insect Repellents
The most common active ingredient found in mosquito repellent coils is oil of citronella. This essential oil is obtained from two different species of lemongrass: cymbopogon nardus (citronella grass) and cymbopogon winterianus (Java citronella). Some mosquito coils have a mix of citronella oil with other essential oils, such as peppermint.
Binding Agents
Many things have been mixed with pesticides and repellents to make mosquito coils. They include:
- Coconut shell flour
- Sawdust
- Ground leaves
- Ground bark
- Corncobs
In the late 1970s, SC Johnson and Son, Inc. was granted a patent to use potato starch as the binder for mosquito coils.
How to Use a Mosquito Coil
Mosquito coils are easy to use, but remember to follow the label’s instructions:
- Use coils on a porch or patio with minimal breeze.
- If you have a multipack, gently separate the coils.
- Follow the manufacturer’s directions to place the coil on a hanger or stand. If using a stand, place it on a flat surface. (Perhaps use a flat dish or tray underneath to catch the ash.)
- If you use a metal or ceramic container, place the coil inside.
- Light the end of the coil and allow it to burn ¼-inch down. Blow out the flame and allow the coil to smolder. If you’re using a container, put the lid on.
- To extinguish, carefully break off the smoldering part and place it in water. Some suggest wrapping the smoldering end in aluminum foil.
Some Safety Tips
Mosquito coils can be a fire hazard, so use caution when handling them:
- Do not use coils inside.
- Don’t use in windy conditions.
- Place on a non-flammable surface. If you hang a coil, place it above a non-flammable surface and put a metal or ceramic dish or container underneath to catch the ash.
- Keep flammable material and liquids away from coils.
- Don’t leave them unattended or in reach of children or pets.
- Don’t put coils in areas where you might step on them.
How Do Mosquito Coils Work?
For starters, the smoke that the coils emit confuses mosquitoes: They can’t smell the scents that we give off, so they can’t target us. Citronella oil works in the same way. Coils with insecticides will kill mosquitoes quickly, or knock them down. (Knockdown is defined as a state of intoxication and partial paralysis that usually precedes death.)
Do Mosquito Coils Work?
When used according to instructions, coils are an effective mosquito control, thus reducing the chances that they’ll bite you. However, studies are mixed as to the length of time that oil of citronella remains effective.
For longer-lasting deterrence, go with the coils that contain insecticide. One study found that coils with natural pyrethrin compounds deterred 45% to 64% of mosquitoes in testing. Another study in Indonesia cited mortality rates of 5% to 100% for the pyrethroids d-allethrin, transfluthrin, and metofluthrin.
For wide-ranging mosquito control, consider coils as one weapon in your battle against the little dive-bombers. Use coils along with other methods to get rid of mosquitoes in your yard, including:
- Get rid of standing water.
- Clean out gutters.
- Cut the grass so mosquitoes have nowhere to rest.
- Spray a mosquito yard spray along thickets and shrubs.
Are There Health Risks in Using Mosquito Coils?
As long as you follow directions, mosquito coils are safe to use. The most important direction — don’t use them indoors. Besides the fire hazard, if you burn a coil in a closed room, you’ll be inhaling concentrations of insecticide or repellent, as well as the chemicals released in the smoke.
However, the ingredients in mosquito coils can trigger some reactions, especially for those with allergies or chemical sensitivities:
Citronella oil: According to the EPA, citronella oil shows little to no health concerns. However, it can irritate the skin and eyes.
Pyrethroids: Generally, pyrethroids are mostly harmless to humans, but they can irritate the skin and eyes. However, d-trans-allethrin can irritate the lungs and trigger asthma-like allergies.
What Are the Health Risks to Pets?
To keep pets safe, the ASPCA suggests that you keep mosquito coils out of reach. Besides the risk of burns, inhaling the smoke (especially with essential oils) can cause respiratory issues. Use particular caution with pyrethroid insecticide coils: Pyrethroids are toxic to cats. The most common, permethrin, can be deadly, PetMD says.
To prevent a curious pet from chewing or swallowing the material, be sure to remove the extinguished coils when you’re ready to go inside. And sweep up any broken coil pieces or ash that lands on the ground.
FAQ
Yes, mosquito coils do work to repel and kill flies. The smoke, as well as repellents like citronella oil, mask any smells that attract flies. Pyrethrins (or their synthetic form, pyrethroids) are used in various insecticides to control flies.
The typical range is five to eight hours. However, at least one brand has coils that last for four hours. Before you buy, check the package or the seller’s description. Manufacturers’ websites may also carry that information.
You can dispose of ash or empty packages by putting them in the trash, per EPA guidelines. Do not put ash down the drain: Pyrethroid is very toxic to fish; citronella oil is slightly toxic. For partially used or unused coils, contact your local solid waste agency or the manufacturer for instructions.
When to Call in a Professional
If you have mosquito problems in areas where it isn’t safe to use coils, then call Pest Gnome, which connects you to the best professional mosquito control services in your area. A local expert has the right tools and methods to banish mosquitoes from your property and to help you keep them away.
Additional sources:
Main Image Credit: gyro / Canva Pro / License
6 comments
Comments are closed.